1. Field of the Invention
The present disclosure relates to a system and method for producing a color palette. In particular, the present disclosure relates to a system and method for producing a color palette including a plurality of color patterns.
2. Background of the Related Art
Currently, the design process for reproducing colors (such as for example, during production of a company logo) begins by using physical color systems in the form of fans or arrays, tables and atlases. The designer selects a color to have reproduced by a specific color reproduction process, such as printing or copying, onto a particular substrate.
The primary goal is to produce a color that closely resembles the color that was originally selected. However, color perception depends on variables including the reproduction process and properties of the substrate. As such, it would be advantageous if a designer could select a color from a color book of samples that were created under substantially the same conditions as the subsequent reproduction. However, creation of such an extensive group of physical color books is not always possible. Furthermore, it would be expensive and cumbersome, and would, among other things, significantly increase the time spent and complicate the sample selection process.
Color perception also depends on illumination, so the reproduction should preferably have a high color constancy. Color constancy refers to the lack of change in the perceived color as the global illumination changes. It also refers to a computation of perceived surface color. Thus, the reproduction should, for as many light sources as possible, generate the same color impression as that of the selected sample in the color system. It is not necessary to replicate or search for the same spectral curve as that of the selected sample (as is customary in color recipe systems), but for a spectral curve which fulfills the desired color constancy.
Thus, it would be especially advantageous for a designer to be able to quickly ascertain whether a certain color can be reproduced with several processes (for example, viewing the color as reproduced by being offset on painted paper and offset on newsprint) with color constancy. A growing tendency exists to create colors for selection on a screen with the help of computer programs. However, such colors are only colorimetrically defined, and spectral curves are not present for the color samples. As previously noted, the presence of a spectral curve for a color is especially advantageous for obtaining color constancy, among other things. For example, metameric effects in the later production process can only be estimated with the help of a spectral curve.
The color systems in use today insufficiently support this design process and have notable disadvantages. They can be classified or characterized as follows:
1. Systems Based on Color Mixing (e.g., Pantone®, HKS, etc.)
These systems are based on a certain number of base colors (for example 14 for Pantone), which are mixed at predefined concentrations with each other in order to maintain the most even and complete coverage possible of the color space. The relationship between concentration and color perception is significantly non-linear in some areas, which makes it difficult to estimate the concentration levels that would comply with the visual equidistance. The conditions of the coloring (or printing) process must be precisely defined (by substrate, print colors, etc.) so that corresponding systems can be generated. Since the color space is defined by way of concentrations, a change of the coloring process is practically made impossible. The color constancy of the samples is not a criterion for the manufacture of such color systems.
2. Systems Based on Color Perception (e.g. Munsell)
The Munsell system is based on the three color perceptions: color tone, brightness and saturation. The main principle of the division of the color space is visual equidistance. Ten visually equidistant base color tones are defined, which in turn are divided into ten equidistant sub color tones. The brightness is also divided into ten individually equidistant levels. Different materials can be used to realize such a color space (e.g., paints or plastic). The criterion of the color constancy can be taken into consideration for the manufacture of such color systems.
A disadvantage common to the two proceeding system types relates to the fact that no mathematical basis exists for the definition of the color space. A further important disadvantage consists in the cost necessary for the manufacture of color atlases for these systems.
3. The CIE System
The Centre Internationale de l'Eclairage (CIE) is an international organization that establishes methods for measuring color. These color standards for colormetric measurements are internationally accepted specifications that define color values mathematically. The first color space model, the CIE “xyz” model, was developed in 1931. CIE defines color as a combination of three axes: x, y, and z. The three points are represented as a tri-dimensional space, known as the color space. The two color spaces released in 1978 are CIE-Lab and CIE-Luv. The CIE system describes how a spectral power distribution can be transformed into a set of three numbers that specifies a color. The three-color coordinates “L, a, b” can be calculated from a color stimulus, such as for example, light source and remission (reflection) of a material. The demand for the visual equidistance is fulfilled to some degree under consideration of special color spacing formulas (DDEcmc, DDE94).
CIE color models are considered to be device independent because the colors should not differ, theoretically, from one output device to another if properly calibrated. CIE color models help move color values from one system to another (e.g., from the Red-Green-Blue color space typically used in monitors to the Cyan-Magenta-Yellow color space typically used in printers), but there is no way to produce colors using CIE values alone. Also, the colors produced by reflective systems, such as photography, printing or paint, are a function not only of the colorants but also of the spectral power distribution of the ambient illumination. If the application has a strong dependence upon the spectrum of the illuminant, spectral matching is required. Thus, a major disadvantage of the CIE system is that the CIE system does not assign color values to a spectral curve.
In view of the aforementioned problems, deficiencies and disadvantages associated with the known color reproduction systems, it would be beneficial to provide a device and/or methodology for providing a color system having an exact mathematical basis for providing the color values and a spectral curve which is assigned to such color values to enhance color constancy.